docs: def unixtime_to_datetime(ut):
      """Convert a unixtime timestamp to a datetime object.
  
      The function converts a timestamp in Unix format to a
      datetime object. UTC timezone will also be set.
  
      :param ut: Unix timestamp to convert
  
      :returns: a datetime object
  
      :raises InvalidDateError: when the given timestamp cannot be
          converted into a valid date
      """
      try:
          dt = datetime.datetime.utcfromtimestamp(ut)
          dt = dt.replace(tzinfo=dateutil.tz.tzutc())
          return dt
      except Exception:
          raise InvalidDateError(date=str(ut))